The growth and development of first-grade writers
Kellogg Hunt's identification and use of the T-unit an independent clause plus all of its subordinate elements as an index of syntactic maturity has greatly influenced the direction and quantity of normative and experimental research in written composition. Among the researchers who have employed mean T-unit length as an index of the chronological development of syntactic ability are Hunt, ODonnell, Griffin, Norris, Stewart, and Witte and Sodowsky. Mean T-unit length has also been used in experimental research as a gauge of the effects of writing instruction and writing curricula on writing performance. Typically, such curricular and instructional research has sought to measure the effects of a particular type of composition course on the syntax of student writers. The two studies completed by Stephen P. Witte and Anne S. Davis suggest that as an individual trait, mean T-unit length may stabilize only after writers have gained writing experience through repeated practice of their writing skills.